A soccer ball is kicked straight upwards with an initial vertical speed of 8.0 meters per second. We can ignore air resistance. How long doe

Question

A soccer ball is kicked straight upwards with an initial vertical speed of 8.0 meters per second. We can ignore air resistance. How long does it take the ball to have a downwards speed of 4.0 meters per second?

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Trung Dũng 6 months 2021-07-26T21:59:10+00:00 2 Answers 99 views 0

Answers ( )

    0
    2021-07-26T22:00:11+00:00

    Answer:

    1.22 seconds

    Explanation:

    Given:

    final velocity ‘vf’ = 8 m/s,

    initial velocity ‘vi’ = -4 m/s (downward, therefore negative)

    accalaration due to gravity ‘g’ = 9.8 m/s²

    ->As the ball undergoes a vertical motion. using the formula

    g = (vf – vi ) / t

    time ‘t’ = (vf – vi )/g

    Substituting all the required values in above eq.

    t = 8-(-4) /9.8  =>  (8+4)/9.8

    t = 12/9.8

    t = 1.22 sec

    Therefore, it takes 1.22 sec for ball to have a downwards speed of 4.0 meters per second

    0
    2021-07-26T22:00:34+00:00

    Answer:

    1.22 s

    Explanation:

    From the question, the ball undergoes a vertical motion.

    Applying

    g = (v-u)/t…………….. Equation 1

    Where g = acceleration due to gravity, v = final velocity, u = initial velocity, t = time.

    make t the subject of the equation

    t = (v-u)/g………….. Equation 2

    Let: The upward be taken as positive direction, and downward be taken as negative direction.

    Given: v = 8 m/s, u = -4 m/s (downward) g = 9.8 m/s²

    Substitute into equation 2

    t = [8-(-4)]/9.8

    t = (8+4)/9.8

    t = 12/9.8

    t = 1.22 s

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